Why Is Coffee Bitter?

When people complain that coffee is bitter, they’re rarely identifying a negative trait found in the bean. Bitterness can suggest a lower-quality bean, but it usually is the result of over-roasting coffee.

Arabica Coffee Isn’t Inherently Bitter, Robusta Is

Most arabica coffee isn’t bitter-tasting, although the lower-grade robusta species can make it taste so. Coffee does contain compounds that taste bitter – most notably caffeine, which is a natural pesticide and herbicide. The majority of the coffee drank in the U.S., however, is good-quality, arabica coffee that doesn’t have many bitter compounds. (Robusta coffee has more caffeine than arabica and, therefore, is more bitter-tasting.)

In fact, coffee, especially quality arabica coffee, has a number of sugars in it. These sugars more than balance out the bitterness of caffeine, which is why coffee that is properly grown, processed, roasted, and brewed can have a sweet taste.

Over-Roasting Creates Bitter-Tasting Coffee

During the roasting process, the sugars that are found in coffee are cooked. They begin to caramelize in the early stages of the roasting process, and the coffee beans begin to change from green to tan, and eventually brown. When properly roasted, the sugars in coffee are caramelized just the right amount, and the resulting coffee isn’t bitter-tasting.

If coffee is roasted too long, however, the caramelized sugars will begin to burn. If the roasting process weren’t stopped, the coffee would eventually become charcoal, which is very bitter. To avoid this, roasters must watch coffee and prevent the sugars from burning. They can become black, burnt and bitter in just a few seconds, though, and roasters must be carefully vigilant throughout the roasting process.

A single misstep along the way could produce a negative trait, like bitterness.

 

If you’ve ever had bitter coffee (and who hasn’t?), it probably wasn’t from the bean but a result of over-roasting. All through the coffee-making process, from growing to brewing, coffee must be carefully attended to, and the roasting phase is no exception. A single misstep along the way could produce a negative trait, like bitterness.

If you do end up with bitter-tasting coffee, take a look at our post on sweeteners to balance out the taste.